Abstract: A detection cell which is used as a component of an optical biosensor comprises a transparent base plate and a sample plate on the base plate. The sample plate has a matrix of wells extending through it to each to receive a sample. The base plate includes a waveguiding film and a diffraction grating means to in couple an incident light field into the waveguiding film beneath a well to generate a diffracted light field to enable detection of a change in the effective refractive index of the waveguiding film.

Abstract: The optical arrangement for an infrared intrusion detector containing a plurality of separate radiation receiving regions or fields of view is provided with a first focussing optic or optical system, for instance a Fresnel lense which receives with its entire surface or area the infrared radiation which arrives from all of the receiving regions and delivers such received radiation to a multiplicity of further focussing means, for instance to individual reflectors. These reflectors are correlated in each instance to one of the receiving regions or fields of view and focus the radiation arriving from such receiving region upon a sensor element. In this way there is attained the beneficial result of optimum utilization of the infrared radiation which is available and the sensitivity of the infrared intrusion detector can be increased. The dimensions of the optical arrangement and the intrusion detector can be maintained small and relatively imperceptible.

Abstract: A method of, and apparatus for, monitoring sound-conducting media wherein sound vibrations are transmitted to and absorbed by the sound-conducting medium. The frequency of the transmitted sound vibrations periodically pass through a predetermined frequency range. During an evaluation period the course of any one of the amplitude or phase of the received sound vibrations are compared with the course of the amplitude or phase during one of the preceding evaluation periods, and when there occur predetermined deviations of both amplitude courses or both phase courses from one another there is triggered an alarm signal.

Abstract: A method of, and apparatus for, monitoring sound-conducting media wherein sound vibrations are transmitted to and absorbed by the sound-conducting medium. The frequency of the transmitted sound vibrations periodically pass through a predetermined frequency range. During an evaluation period the course of any one of the amplitude or phase of the received sound vibrations are compared with the course of the amplitude or phase during one of the preceding evaluation periods, and when there occur predetermined deviations of both amplitude courses or both phase courses from one another there is triggered an alarm signal.

Abstract: To detect breakage of glass panes, panels of display cases, or movement in a room, ultrasonic waves, preferably in the order of from 120 kHz to 180 kHz, are transmitted to the sonically conductive medium (glass panes, plastic sheets, or into the air of the room), and the waves are received in a receiver. The time shift of the received waves at the receiver location, with respect to the transmitted waves is determined, and if this time shift changes beyond a predetermined limit, an alarm signal is generated. Preferably, the ultrasonic signals are frequency modulated, for example by shifting the generated waves by a predetermined frequency shift, and determining the temporal change, or delay of the frequency shift, as received, with respect to the time of frequency shift at the transmitter. To prevent the effect of drift, the rate of change of received with respect to transmitted frequency shift can be used to generate the alarm.